The present invention relates generally to the field of cell based therapies. More specifically, the present invention relates to the derivation of hepatic stem cells from stem cells derived from non-liver tissue.
Liver failure secondary to hepatitis, hepatotoxin exposure, and cirrhosis threatens the lives of thousands in the United States alone. Estimates of yearly direct healthcare costs for liver disease in the U.S. range from $60 billion to over $100 billion. An additional $20-40 billion in disability is paid annually to these patients and their families by the Social Security Administration. Unfortunately, at this time, liver transplantation is the only therapeutic option available to patients other than palliative measures.
However, because of the shortage of donor organs, less than a third of all patients on waiting lists for livers will actually receive one. According to the United Network of Organ Sharing (UNOS), 15,700 patients await liver transplantation in the United States currently, but only 4,000 to 5,000 transplantable donor livers are available annually. Since, with few exceptions, one donor organ helps only one recipient, over the past decade an increasing gap has grown between available donors and waiting transplant candidates. Therefore, novel therapies are needed.
Stem cell therapies present an alternative therapeutic option for those requiring whole or partial reconstitution of liver function. In many ways, liver cell therapies are a desirable alternative to whole organ transplantation, because one liver can be used to treat multiple patients and because the surgical procedures involved in cell therapies are safer, easier, and less costly for the patient. Stem cell transplantation offers a treatment modality that safely and effectively improves biochemical function within the failing liver.
Thus, there is a need for methods to derive hepatic stem cells from non-liver tissue.